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Music and the Brain (Digest)

BlogMS original blog key: 1000074313, blog id: airoff History stat: 浏览/评论:204/0 , 日期:2004年10月27日 15:22

The brain might not have a specific center for music.

More recent work has yielded a more nuanced understanding, relating to two of the features that music and language share: both are a means of communication, and each has a syntax, a set of rules that govern the proper combination of elements (notes and words, respectively). According to Aniruddh D. Patel of the Neurosciences Institute in San Diego, imaging findings suggest that a region in the frontal lobe enables proper construction of the syntax of both music and language, whereas other parts of the brain handle related aspects of language and music processing.

Although most research has focused on melody, rhythm (the relative lengths and spacing of notes), harmony (the relation of two or more simultaneous tones) and timbre (the characteristic difference in sound between two instruments playing the same tone) are also of interest. Studies of rhythm have concluded that one hemisphere is more involved, although they disagree on which hemisphere. The problem is that different tasks and even different rhythmic stimuli can demand different processing capacities. For example, the left temporal lobe seems to process briefer stimuli than the right temporal lobe and so would be more involved when the listener is trying to discern rhythm while hearing briefer musical sounds.

Learning retunes the brain, so that more cells respond best to behaviorally important sounds. This cellular adjustment process extends across the cortex, "editing" the frequency map so that a greater area of the cortex processes important tones. One can tell which frequencies are important to an animal simply by determining the frequency organization of its auditory cortex.

The long-term effects of learning by retuning may help explain why we can quickly recognize a familiar melody in a noisy room and also why people suffering memory loss from neurodegenerative diseases such as Alzheimer’s can still recall music that they learned in the past.

The temporal lobe is needed to comprehend melody but not to produce an emotional reaction, which is both subcortical and involves aspects of the frontal lobes.

Consonant chords activated the orbitofrontal area (part of the reward system) of the right hemisphere and also part of an area below the corpus callosum. In contrast, dissonant chords activated the right parahippocampal gyrus. Thus, at least two systems, each dealing with a different type of emotion, are at work when the brain processes emotions related to music.

Music activated some of the same reward systems that are stimulated by food, sex and addictive drugs.

Overall, findings to date indicate that music has a biological basis and that the brain has a functional organization for music. It seems fairly clear, even at this early stage of inquiry, that many brain regions participate in specific aspects of music processing, whether supporting perception (such as apprehending a melody) or evoking emotional reactions. Musicians appear to have additional specializations, particularly hyperdevelopment of some brain structures. These effects demonstrate that learning retunes the brain, increasing both the responses of individual cells and the number of cells that react strongly to sounds that become important to an individual.